One of the factors affecting the design of a wireless communications system is the channelization requirement. It is customary that the requirement of a wireless communications system starts by defining the channelization of the system. Based on the channelization requirement, features are developed to address the characteristics and the requirements of the channel.
The globalization of wireless communications system creates new challenges. One of them is the difference in channelization of a wireless communications system in different countries. For example, in U.S and Europe, IEEE 802.11ac defines UNI 1, 2 and 3 bands for 80 MHz and 160 MHz channels, but in China, only UNI 3 band is currently available for IEEE 802.11ac systems.
The Chinese UNI 3 band is 125 MHz wide and is slightly offset as compared to the US UNI bands. If US channelization is used, a significantly amount of bandwidth will be wasted. As a result, the channel bandwidth for IEEE 802.11ac in China must be wider than the ones defined in the US, etc. The difference in the channel bandwidth creates co-existence and backward compatibility among communications devices operating in different channel bandwidth. The main reason for the incompatibility is the central frequency of the wireless band is shifted with respect to the corresponding channel width. A solution is sought.